1. Field of the Invention
The present invention relates to a technology for setting allocation of database data in a computer system.
2. Description of the Related Art
In a computer system that handles database containing large amount of data, the database data is generally stored in physical storage areas (such as disks) belonging to a storage device system (such as a storage system). A database management system (hereinafter ‘DBMS’) that runs on a computer belonging to the computer system performs database-related processing accessing the database data stored in the physical storage areas of the storage device system. Consequently, DBMS processing performance is affected by data access performance for the physical storage areas in which the database data is stored. The data access performance for the physical storage areas fluctuates depending on the frequency with which the data stored in each physical storage area is accessed by the DBMS. Therefore, in order to increase DBMS processing performance, it is important to set allocation of the database data in the physical storage areas while taking into consideration the frequencies with which the physical storage areas are accessed.
A technology is described in JP2003-150414A, for example, for estimating the access frequencies for the physical storage areas using allocation information that indicates the relationships between a table or the like composing a database and the physical storage areas in which the table or other data is stored, as well as history information regarding processing commands (such as SQL phrases) executed by the DBMS. A technology is also described in U.S. Pat. No. 6,035,306, for example, for notifying an administrator of a problem about the allocation of database data within physical storage areas using allocation information that indicates the relationships between a table or the like composing a database and the physical storage areas in which the table or other data is stored, as well as the results of monitoring of the access frequencies for the physical storage areas.
In general, the data for tables or the like composing a database is divided and allocated across multiple physical storage areas. There are often variations in data storage density among the various physical storage areas, as well as variations in the frequency of DBMS access, depending on the table and other data allocated to each physical storage area. Furthermore, these variations often change during database use. Consequently, using the above prior art technologies, it is difficult to accurately monitor or estimate the access frequencies for the various physical storage areas, making it difficult to set the allocation of database data among the various physical storage areas while taking into account the physical storage area access frequencies.